First, test the ripped WAV to listen for any pop at the end. If there's something there, then it will obviously be present in the encoded file. If it's clean then you can start to look at your encoder settings.

Sorry, Bruno, but this might not be correct.

Different pieces of player software might interpret the added data differently. One player might recognize it as a "tag" and skip it, while another might attempt to play every byte up until the end of the file.

The only critical thing is, if there's ASCII text appended to the file, does the MP3 encoder regognize and handle the text, or does it try to encode it? This could be completely different behavior than his WAV-player app.

The reason I say this, is when we were trying to debug the popping problem all those years ago, we kept going back and listening to the original WAV file and it always sounded fine, with no pops. Well, that was because the only app we had which could play WAV files that large was SoundForge, the very program that appended the data in the first place. So of course it skipped the tag on playback. Because of this, it took us longer to find the root of the problem than it should have.